In general, obvious grooves on the stool and frequent diarrhea are considered to be related to intestinal polyps and colorectal cancer. 1. Intestinal polyp: it is a bulging lesion on the surface of intestinal mucosa that protrudes into the intestinal lumen, which can be induced by chronic inflammatory stimulation, heredity, diabetes, etc. When the polyp is large, it can affect the character of stool and appear obvious grooves. When the polyp is large, it can affect the character of stool, appearing obvious grooves and accompanied by diarrhea. 2. Colorectal cancer: refers to malignant tumors occurring in colon or rectum, with rectal cancer being the most common. Rectal cancer can be manifested by blood in stool, changes in bowel habits and stool characteristics, such as grooves in stool and frequent diarrhea. It is recommended to seek medical treatment immediately for the above symptoms, so as to make a clear diagnosis and carry out targeted treatment under the guidance of professional physicians.